Iridium update

Iridium v1.05b has been release.
It includes a lot of changes:

• New music (more being added) and sound effects
• User music (OGG and old school trackers) can now be added
• Updated to use the latest DirectXTK rather than the legacy D3DX libraries (image loading)
• Now built using Visual Studio 2019 rather than 2015
• New screen initialisation routines 
• Screen grabs captured with the Print Screen key